The overall aim of this research is to define the structures of the carbohydrate units in glycoproteins involved in blood coagulation and to elucidate the role of the sugars in the biological activity. During the coming year, we expect to complete the studies on thrombin. Subsequent elucidation of the carbohydrate structures of the prothrombin activation fragments, will also provide all the data required for the carbohydrate structure of prothrombin. Having completed most of the required enzymatic analyses for the sugar sequences, subsequent work will involved permethylation studies to determine the linkage points and possibilities of branching. The effect of sugar removal on coagulant activity will also be studied. It is also planned to conduct parallel investigations with factor X.